This invention relates, in general, to print elements and more particularly to a mounting assembly for a daisy wheel print element employed in serial printers.
The Diablo Corporation, a subsidiary of the present assignee, is marketing a serial printer under the tradename of Diablo Hytype I, which employs a movable carriage with a daisy type print wheel, print hammer and ribbon cartridge mounted thereon. A printer of this type is disclosed in a U.S. patent application filed Sept. 4, 1973, in the name of Andrew Gabor, Ser. No. 394,072, abandoned, entitled "High-Speed Printer with Intermittent Print Wheel and Carriage Movement", being a continuation of an application filed Feb. 25, 1972, Ser. No. 229,314, abandoned, the disclosure of which is incorporated by reference into this specification.
The Diablo Hytype I printer is enjoying commercial success as a serial printer in such applications as communication terminals, computer output devices, etc. However, in certain type applications, such as automatic text-editing typewriter applications in the office environment, additional features and capabilities are desired, e.g., higher print quality. In the text-editing or office-typing environment, the demands for high print quality cause the print wheel to be subjected to about ten times greater force due to about five times greater hammer energy compared to a Hytype I printer operating as a computer output terminal, for example.
A modified model of the Hytype I printer is employed as the printing mechanism of the commercially available Xerox 800 Electronic Typing System for automatic text-editing typewriter applications in the office environment. To provide the high print quality needed, the integrally molded thermoplastic print wheel of the Hytype I printer was replaced by a composite print wheel such as that disclosed in a U.S. patent application, filed Sept. 25, 1974, in the name of Gordon Sohl et al, Ser. No. 509,193 abandoned. In addition, a different print hammer assembly was incorporated therein which provided greater hammer energy. A card guide was added to the carriage to provide assistance in the operation of inserting and aligning paper in the automatic textediting typewriter. The Diablo Hytype I ribbon cartridge containing a fabric ribbon was replaced by a ribbon cartridge containing a matrix-type plastic ribbon from which a higher quality of printed material may be obtained.
In the environment provided by the modified printer, the spacings between the paper, ribbon and composite print wheel are extremely close because of the modifications (addition of a card guide and the thicker character slugs of the new composite print wheel) to the printer. The additional weight and inertia of the composite print wheel make the mounting of the print wheel more important than the mounting of the prior art print wheel or element. When it is necessary to change the print wheel on the printer to another print wheel, it is important to be able to easily and positively remove the print wheel and attach the replacement print wheel so that neither print wheel is damaged.
With these requirements in mind, it is a primary object of the present invention to design a simple and reliable means for mounting a print element in a serial printer.
Another object of this invention is to provide an improved print element mounting assembly.
Yet, another object of the current invention is to design a print element mounting assembly which provides a tightening force around the shaft of the print element motor.
Other objects and advantages of the present invention will be evident from the specification and claims when read in conjunction with the accompanying drawing illustrative of the invention.